Conventional networks can join various devices including, for example, client devices (e.g., computers, printers, Internet fax, personal data assistant, mobile phone, other network adapters, etc.), server devices (e.g. data server, proxy server, time-server, etc.), and other network devices (e.g., routers, which interconnect, for example, multiple subnets of a network). The network allows data to be communicated between devices on the network. Conventional network devices are assigned a unique address that identifies the device on the network as well as facilitates communication between devices. For example, in a computer network utilizing the internet protocol (IP) standard, each device on the network is assigned a particular IP address.
An IP address can be static or dynamic. A static IP address is the same for a device each time the device connects to a network. A dynamic IP address, by contrast, is an IP address that is typically assigned to a device e.g., by a server for a specified time. The dynamic IP address can change, for example, after the specified amount of time has elapsed or each time the device accesses the network.
One protocol for assigning dynamic IP addresses is dynamic host configuration protocol (DHCP). DHCP defines a set of rules used to allow network devices to request and obtain an IP address from a DHCP server. A DHCP server can be a network server. However, other devices can act as a DHCP server including e.g. routers and firewalls. The DHCP server can include a collection of IP addresses available for assignment. Typically, an IP address is assigned for a specified period of time (e.g., an hour), after which the IP address is available for assignment to another device. Consequently, the IP address of a particular network device can vary over time. This assignment of an IP address for a specified period of time will be referred to in this specification as a lease.